Dopamine (DA), norepinephrine (NE), and epinephrine (EPI) and their metabolites and dopamine-Beta-hydroxylase (DBH) are present in human plasma and cerebrospinal fluid (CSF). Levels of these substances reflect the balance between their release and removal. The increases in levels of NE and EPI with standing, exertion, stress, drugs, administration, etc., are used to examine sympathetic neuronal responsitivity. The responses and level of activity of the activity of the sympathetic nervous system in cardiovascular disorders (hypotension) in alcoholism, a variety of psychiatric disorders, and after treatment with drugs are being examined. Dopamine-beta-hydroxylase (DBH) is the enzyme which converts dopamine (DA) to NE. NE and DBH can be measured in cerebrospinal fluid (CSF) and may be useful to estimate in disease in which a defect is suspected, i.e., essential hypertension, Shy-Drager syndrome, amyotrophic lateral sclerosis (ALS), enuresis and hyperactivity in children, and schizophrenia.